In a mechanical press equipped with tooling modules or stations for producing aluminum top end walls or shells for aluminum beverage cans, for example, as disclosed in U.S. Pat. No. 5,042,284 which issued to the assignee of the present invention, a batch of aluminum shells are produced with each stroke of the press. The shells are discharged from one side of the press through tubular guide chutes and by air jets, for example, as disclosed in FIG. 11 of the above patent. The guide chutes sometimes extend to endless belt conveyors which convey the shells to curling machines for rolling the peripheral lip portions of the shells inwardly to facilitate attachment of the shell to the rim portion of an aluminum can. The conventional curling machine includes a rotary curling wheel and a peripherally extending curling die for each of the belt conveyors, and each belt conveyor usually receives the shells discharged through guide chutes extending from two or more tooling stations within the press.
It has been found desirable to increase the number of tooling stations within a single or double action mechanical press and for the press to receive a wider strip of aluminum stock so that a larger batch of shells may be produced with each stroke of the press. For example, if shells are produced in a press operating over 400 strokes per minute and having 22 tooling stations and equipped for receiving an aluminum strip having a 52 inch width, the shells are produced more efficiently and at a substantially higher volume per minute. However, when producing shells at such a high rate, there is a problem of controlling the flow of shells from the tooling stations onto the endless belt conveyors so that the shells do not overlap and are fed to the curling machines in single file. Furthermore, a large number of rotary curling machines is required to handle the high flow rate of shells, and the machines require substantial floor space in addition to the investment in the curling machines.
In order to reduce the number of curling machines required for handling a larger flow rate of shells, a pair of rotary curling wheels have been mounted on a common drive shaft in axially spaced relation with each wheel positioned to receive the shells being delivered by one conveyor belt. Such a curling machine has been produced by E. W. Bliss Co. in Hastings, Mich.